154 citations · 418 across the 20 of their papers we have counts for
21 papers
Beyond the Damped Random Walk: Multiband AGN Variability from SDSS to Rubin LSST
Izak Schmidlkofer, Zhirui Hu, Weixiang Yu +1
The flux variability of Active Galactic Nuclei (AGNs) is commonly modeled using the damped random walk (DRW), but increasingly rich multiband time-domain surveys motivate more flex…
Multivariate Continuous-Time Autoregressive Moving Average Processes for Astronomical Multiband Time Series
Izak Schmidlkofer, Zhirui Hu, Lishan Shi +2
Large-scale astronomical surveys provide unprecedented volumes of multivariate time-series observations obtained through multiple optical filters. We develop a structured multivari…
Modeling Dependence Structures in Astronomical Multi-Band Time Series Data via Multi-Output Gaussian Processes
Samata Das, Lishan Shi, Yasaman Hamayouni +2
Modern astronomical time-domain surveys routinely collect multi-band light curves that provide complementary information about the physical processes governing source variability.…
Six Maxims of Statistical Acumen for Astronomical Data Analysis
Hyungsuk Tak, Yang Chen, Vinay L. Kashyap +4
The production of complex astronomical data is accelerating, especially with newer telescopes producing ever more large-scale surveys. The increased quantity, complexity, and varie…
Mapping the Growth of Supermassive Black Holes as a Function of Galaxy Stellar Mass and Redshift
Fan Zou, Zhibo Yu, W. N. Brandt +3
The growth of supermassive black holes is strongly linked to their galaxies. It has been shown that the population mean black-hole accretion rate () prima…
A Robust Bayesian Meta-Analysis for Estimating the Hubble Constant via Time Delay Cosmography
Hyungsuk Tak, Xuheng Ding
We propose a Bayesian meta-analysis to infer the current expansion rate of the Universe, called the Hubble constant (), via time delay cosmography. Inputs of the meta-analysis…
Practical Guidance for Bayesian Inference in Astronomy
Gwendolyn M. Eadie, Joshua S. Speagle, Jessi Cisewski-Kehe +5
In the last two decades, Bayesian inference has become commonplace in astronomy. At the same time, the choice of algorithms, terminology, notation, and interpretation of Bayesian i…
TD-CARMA: Painless, accurate, and scalable estimates of gravitational-lens time delays with flexible CARMA processes
Antoine D. Meyer, David A. van Dyk, Hyungsuk Tak +1
Cosmological parameters encoding our understanding of the expansion history of the Universe can be constrained by the accurate estimation of time delays arising in gravitationally…
Incorporating Measurement Error in Astronomical Object Classification
Sarah Shy, Hyungsuk Tak, Eric D. Feigelson +2
Most general-purpose classification methods, such as support-vector machine (SVM) and random forest (RF), fail to account for an unusual characteristic of astronomical data: known…
Time Delay Lens Modelling Challenge
X. Ding, T. Treu, S. Birrer +26
In recent years, breakthroughs in methods and data have enabled gravitational time delays to emerge as a very powerful tool to measure the Hubble constant . However, published…
Modeling Stochastic Variability in Multi-Band Time Series Data
Zhirui Hu, Hyungsuk Tak
In preparation for the era of the time-domain astronomy with upcoming large-scale surveys, we propose a state-space representation of a multivariate damped random walk process as a…
Data transforming augmentation for heteroscedastic models
Hyungsuk Tak, Kisung You, Sujit K. Ghosh +2
Data augmentation (DA) turns seemingly intractable computational problems into simple ones by augmenting latent missing data. In addition to computational simplicity, it is now wel…
How proper are Bayesian models in the astronomical literature?
Hyungsuk Tak, Sujit K. Ghosh, Justin A. Ellis
The well-known Bayes theorem assumes that a posterior distribution is a probability distribution. However, the posterior distribution may no longer be a probability distribution if…
Robust and Accurate Inference via a Mixture of Gaussian and Student's t Errors
Hyungsuk Tak, Justin A. Ellis, Sujit K. Ghosh
A Gaussian measurement error assumption, i.e., an assumption that the data are observed up to Gaussian noise, can bias any parameter estimation in the presence of outliers. A heavy…
Rapid Optical Variations Correlated with X-rays in the 2015 Second Outburst of V404 Cygni (GS 2023338)
Mariko Kimura, Taichi Kato, Keisuke Isogai +24
We present optical multi-colour photometry of V404 Cyg during the outburst from December, 2015 to January, 2016 together with the simultaneous X-ray data. This outburst occurred le…
Frequency Coverage Properties of a Uniform Shrinkage Prior Distribution
Hyungsuk Tak
A uniform shrinkage prior (USP) distribution on the unknown variance component of a random-effects model is known to produce good frequency properties. The USP has a parameter that…
Rgbp: An R Package for Gaussian, Poisson, and Binomial Random Effects Models with Frequency Coverage Evaluations
Hyungsuk Tak, Joseph Kelly, Carl N. Morris
Rgbp is an R package that provides estimates and verifiable confidence intervals for random effects in two-level conjugate hierarchical models for overdispersed Gaussian, Poisson,…
Bayesian Estimates of Astronomical Time Delays between Gravitationally Lensed Stochastic Light Curves
Hyungsuk Tak, Kaisey Mandel, David A. van Dyk +3
The gravitational field of a galaxy can act as a lens and deflect the light emitted by a more distant object such as a quasar. Strong gravitational lensing causes multiple images o…
A Repelling-Attracting Metropolis Algorithm for Multimodality
Hyungsuk Tak, Xiao-Li Meng, David A. van Dyk
Although the Metropolis algorithm is simple to implement, it often has difficulties exploring multimodal distributions. We propose the repelling-attracting Metropolis (RAM) algorit…
Data-dependent Posterior Propriety of Bayesian Beta-Binomial-Logit Model
Hyungsuk Tak, Carl N. Morris
A Beta-Binomial-Logit model is a Beta-Binomial model with covariate information incorporated via a logistic regression. Posterior propriety of a Bayesian Beta-Binomial-Logit model…
Strong Lens Time Delay Challenge: II. Results of TDC1
Kai Liao, Tommaso Treu, Phil Marshall +23
We present the results of the first strong lens time delay challenge. The motivation, experimental design, and entry level challenge are described in a companion paper. This paper…